How check/uncheck checkbox on parent form if records do or do not exist in subform

If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Unanswered: How check/uncheck checkbox on parent form if records do or do not exist in subform

I have a parent form which has a yes/no checkbox in the form's record source. Then in that parent form I have a sub-form. If NO records exist in the sub-form I want the checkbox to be UN checked. If records DO exist in the sub-form, I want the checkbox to be CHECKED.

But I want this to happen as records are added or deleted from the sub-form. In other words, if the parent form is opened and no records exist in the subform then the checkbox should be unchecked. But as soon as the first record has been entered in the subform, the checkbox on the parent form should be checked. Likewise, as soon as the last record has been revoved from the sub-form, the checkbox on the parent form should be unchecked.